FIELD OF THE INVENTION
The invention relates to an apparatus for deflecting the flow of a fluid, such as a gas or a flue gas from an inflow conduit, through a deflection zone and into an outflow conduit that is angled relative to the inflow conduit by a deflection angle, and possibly into a deNO.sub.x catalytic converter.
In many industrial fields there is a need for deflecting the flow of a fluid. The fluid flows from an inflow conduit through a deflection zone into an outflow conduit that is bent at an angle relative to the inflow conduit. Reverse-flow zones, eddies and turbulence can develop in the deflection zone with the creation and dimension thereof depending on various physical variables, in particular the flow velocity in the inflow conduit, the density and viscosity of the fluid, and the geometry of the inflow conduit, the deflection zone and the outflow conduit. Among other effects, that causes the flow of fluid to lose energy, and upon entry of the fluid into the outflow conduit, the flow has an uneven velocity profile.
In process technology, there is often a requirement to deflect a flow of a gas from an inflow conduit into an outflow conduit, and the cross-sectional area of the inflow conduit may be smaller than that of the outflow conduit. The flow of the gas should already have a uniform flow profile soon after entering the outflow conduit. That is of special significance, for instance, for supplying a flow of gas containing dust to an electrostatic dust separator, or upon the inflow of combustion air into a zoned grate for the sake of uniform combustion of coal, and in a conventional power plant for an oncoming flow against a deNO.sub.x catalytic converter, where stringent demands are placed on the flow of flue gas in terms of its flow profile.
For the sake of meeting the requirements for the flow profile, depending on the fluid-technology application, provision is made, for instance in conventional power plants where there is an oncoming flow against deNO.sub.x catalytic converters, to provide guide vanes, typically in the deflection zone, between which the fluid flows and is deflected in the process. The guide vanes are constructed in accordance with operating conditions, in particular the geometry of the conduit and the physical characteristic variables of the fluid, such as the Reynolds number, the viscosity and the density. In order to provide for their construction, either comprehensive and possibly parameter studies must be made, or recourse to information in the literature is necessary. Due to the special geometry of the guide vanes, they are expensive to produce and sometimes require special manufacturing processes and relatively major consumption in terms of materials. The securing of the guide vanes must be adapted to the applicable operating conditions and must be constructed for the forces (buoyancy) and moments that occur in each case. Furthermore, retrofitting of guide vanes into existing conduits with deflection zones may be extremely difficult.
Solid particles, particularly dust particles, entrained in the flow are deposited primarily on negative-pressure sides of the guide vanes. A danger exists of relatively large quantities of solid particles that have accumulated at the guide vanes slipping from them and getting into the outflow conduit. That can cause damage to devices that are disposed in or downstream of the outflow conduit, and particularly can cause plugging up of catalytic converters.
German Patent DE 39 23 134 C2 describes an apparatus for deflecting a flow from a first conduit into at least one second conduit which is disposed at an angle relative to the first conduit, with a transitional region between the two conduits. Baffles that are essentially parallel and are spaced apart by the same distance from one another and form lanes are disposed in the transitional region. In the axial direction of the first conduit, they progressively increasingly protrude from the second conduit into the transition region. The baffles are rotated relative to the axis of the first conduit by an acute angle, in other words an angle of less than 90.degree.. The total flow is split into partial flows that are carried through the lanes of the apparatus. The baffles are flat and on a downstream edge each has at least one segment protruding from the plane of the baffle. The segment forms an acute or right angle with the baffle and thus brings about the development of an eddy zone within and downstream of the respective lane and a flow backup at the end of each lane. As a result of the eddy zones, flowing down and evening out of the flow is intended to be obtained in the second conduit. The eddy zones in the lanes and the partial currents flowing through the lanes are in a state of mass transfer with one another, and as a result solid particles entrained in the partial flows reach the eddy and backup zones and can accumulate there. As a result of an accumulation or deposit of large quantities of particles, the danger exists in that apparatus as well that relatively large quantities of solid particles entrained in the flow will suddenly reach the second conduit.